Index: /trunk/src/VBox/Main/MachineImpl.cpp
===================================================================
--- /trunk/src/VBox/Main/MachineImpl.cpp	(revision 30297)
+++ /trunk/src/VBox/Main/MachineImpl.cpp	(revision 30298)
@@ -4066,13 +4066,13 @@
 {
     ULONG64 dummyTimestamp;
-    BSTR dummyFlags;
-    return GetGuestProperty(aName, aValue, &dummyTimestamp, &dummyFlags);
+    Bstr dummyFlags;
+    return GetGuestProperty(aName, aValue, &dummyTimestamp, dummyFlags.asOutParam());
 }
 
 STDMETHODIMP Machine::GetGuestPropertyTimestamp(IN_BSTR aName, ULONG64 *aTimestamp)
 {
-    BSTR dummyValue;
-    BSTR dummyFlags;
-    return GetGuestProperty(aName, &dummyValue, aTimestamp, &dummyFlags);
+    Bstr dummyValue;
+    Bstr dummyFlags;
+    return GetGuestProperty(aName, dummyValue.asOutParam(), aTimestamp, dummyFlags.asOutParam());
 }
 
@@ -4192,5 +4192,5 @@
             mData->mSession.mDirectControl;
 
-        BSTR dummy = NULL;
+        BSTR dummy = NULL; /* will not be changed (setter) */
         ULONG64 dummy64;
         if (!directControl)